Frequency identification circuits are used in various signal processing and telecommunication applications. A problem with prior art frequency identification circuits is that the circuits typically are designed for a specific application and identify a frequency only within a specific band. For example, Ikeda (U.S. Pat. No. 4,334,273) discloses an apparatus for detecting the tone signal in a telephone switching system using a discrete Fourier transform process. As another example, Wondergem et al (U.S. Pat. No. 4,395,762) discloses a frequency counter for processing the output of a proton precession magnetometer. In addition, prior art frequency identifier circuit designs have tended to be complex.